texas. southern colorado, oklahoma, west virginia and ohio. and so it seems like sort of a new phenomenon certainly in the news lately, but it's actually not. this sly slide is to give you a feel for what's been a phenomenon known for more than 50 years now. here's a list of either the largest or the most significant earthquakes in several different areas. and due to several different human activities around the world. starting with back in the '60s and a colin injection experiment, rocky mountain, i want you to remember this one. this is the largest well documented injection induced earthquake, 9.253. in are want -- in the former soviet union, three earthquakes, not necessarily due to injection. we don't know what happened there. but certainly due to the human gas extraction activities. water reservoirs, large water

reservoirs also trigger earthquakes, as in lake mead in nevada and orville in california. and many other places around the world. and also geothermal, the geothermal field, where the injection has resulted in an earthquake, and a few others that do -- that you probably have heard. so it's not a new phenomenon. we understand why this happens fairly well. it's just actually very difficult to predict when it's going to happen, and the research program we're working on is what to do about it when it does happen. many of these, as you see, are related to the injection activity, and that's what i'm going to focus my remarks on tonight. those activities that humans are involved with and entail are -- involve food injection in depth or waste, liquid disposal of all

types. disposal into wells and earth. geo they we geothermal production, as i mentioned. and these three production activities -- that doug described, tight shale gas, tight sand, coal bed, methane, can involve fracking. and the associated need to dispose of formation water, fluids that dennis described. also, in the future, sitting out there as carbon dioxide sequestration, there are some pilot projects now, but should carbon dioxide geologic sequestration become -- this will involve the injection of fluid into the earth with the potential of triggering earthquakes. so through the chesapeake video that you saw at the beginning and dennis's talk, i think you understand this process well now. the formation where the gas is, it's fracked, and that fracking

process may use 1 million or some millions of gallons of water in order to extract the gas what occurs after the formation, after the rock is fractured and during the production stage, during that video which you saw with the little red bubbles bubbling up to the surface is that water has returned to the surface. this formation fluid that brines that dennis described that can be quite salty. and that has to be disposed of somehow. in some cases, it can be recycled, as dennis described. in other cases, it can be sent to a water treatment plant. however, in many cases, there's such a large volume of fluid

that comes up with this brian that it's not economic for that to be disposed of at a water treatment plant or to be recycled and it's disposed of through a disposal well. that process is -- illustrated in this cartoon, the fracking occurs. the formation fluid is returned to the surface, it's sent off to a disposal where it's injected deep. typically, to a depth that has the potential for storing enough energy to trigger an earthquake. most of the time, that doesn't occur. and that's really worth keeping in mind. even though we have some very noteworthy cases where it has occurred. this can be a very large amount of fluid, and fluid from several of the production wells may be tapped into the same disposal -- typically is tapped into the same disposal well. i illustrate here what a well head looks like, but also the other phenomenon here that's of

interest is the trucking of this, which dennis described for the fracking operation. there is also trucking that can be associated with the disposal operation. and the earthquake that was triggered -- all the earthquakes that have been triggered over the last year in youngstown, ohio, that's fluid that's being disposed of there is actually formation water, produced water from the fracking activities in pennsylvania. there is no fracturing in youngstown, ohio. so why does this happen? i'll try to lead you through this, in a simple way. first, it's important to understand that once you get a few kilometers deep in the earth, the earth is everywhere stressed. and, of course, the earth is pervasively fractured and faulted. so from stress measurements made across the united states, we actually know that these natural stresses put fault and fractures close to failure.

there's -- the difference in the rate of earthquakes in the west and the rate of earthquakes in the east is not because there's no stress in the east. it's because there's a much higher rate of deformation in california and alaska, for example. so the natural stresses put defaults in fractures close to failure. and then when you inject water, any fluid, into the rock at depth, that forces the fluid along those fractures at high pressure, and relieves what is called the effective stress on that fault. essentially, the fluid pushes the sides of the fault apart. which is easy to imagine. but what it does, it allows that fault to slip more easily than it would have, had it not been pressurized. so the injection activity pushing large volumes and high pressure down deep into rock which is already stressed is what's allowing the earthquakes to be triggered. the formation of new fractures,

that is the hydro fracture, actually doesn't release very much energy compared with these larger triggered earthquakes. the hydro frac, the earthquakes would typically be less than 9.22. and there would be lots of them. and they're not really a safety concern. it's really the injection of the dispose -- of the fluids that have to be disposed of that are a consequence of the production operation that has the potential to trigger earthquakes. and i think i just made my last point. is this a significant phenomenon in the united states? this dwraf, i'll try to walk through with you to -- it is a very significant phenomenon in the united states. although it is localized. and, of course, the earthquakes have not been all that large. but what my colleague bill

elsworth has done is a very simple exercise, which is simply to count the number of earthquakes. and they're counting all the earthquakes in the central part of the united states between these two bars that are larger than 92.3 from 1970 through most of last year. that -- this is -- count is not representative of the size. it's just the number of earthquakes of any size between '92 and '93. and what you see here is a fairly constant rate of earthquakes from 1970 through about year 2000. that's about -- average of 21 earthquakes per year, and a fairly steady rate. and we believe that the catalog complete for this magnitude level, back to 1970. so this is representative of a pretty stable process of earthquake generation in the central united states. then what happens, in about the year 2000, the turn of the

century, 2000, 2001, is that rate increases and that's shown by this green line here. it increases by about 50%. and we -- associate that -- there's a large proportion of those what you might call excess earthquakes that are occurring in colorado and they're associated with the production of coal bed methane. then in about 2008, that rate goes up again. it goes up quite significantly. in fact, it's more than seven times larger than the long-term average. and this -- this rate is something that really cannot be explained by any natural process. during this time period, we don't have any large earthquakes in the central u.s. that would have a large series of aftershocks which would bump up the numbers. pretty stable rate during this entire time of earthquakes but then it jumps up at this larger rate. so this is what we interpret to be a human-induced process.

and geographically, it's associated with these enhanced recovery activities that previous two speakers talked about. i'll give you an example of one of them. this is the induced earthquake near guy, arkansas. and guy, arkansas is right here. and the injection in the area -- this is a shale gas play, enhanced recovery, fracking operation and disposal, as was described earlier, the triangles here that are a one, two, three, four, five through eight are the disposal wells in the area. not shown in the production wells. and then these numbers are size mow graphs deployed by the university of memphis, one of our partners. and so these are recording earthquakes, and the earthquakes are shown here in yellow and red. and they represent a progression

in time. the red earthquakes occurring earlier, and then migrating down to the south, along what is quite obviously a fault in the rock over a period of about a year-and-a-half. so the fault is the with-defined. this fault is obviously then a conduit for the injected fluids. and it's that fault that's responsible for having produced this magnitude 4.7 earthquake. what makes this a particularly useful case -- triggered earthquake scientifically is that after the 4.7 earthquake, the arkansas oil and gas commission halted the injection at two of the wells, and very promptly, the -- the earthquake sequence died down. that's the kind of smoking gun that is very helpful to have when somebody says how do you know those earthquakes were triggered, how do you know they're not natural earthquakes, because there are natural earthquakes in arkansas. well, the fact that that sequence died as soon as those wells were -- their disposal

activities were halted by the oil and gas commission, provides that evidence. then later they started up a third well, injected fluid, and the earthquake started up again. so we have a very well-established case. this is published in the current issue of size mow logical research, if you want to see the gory details. so the research questions are these, just to put them simply. why do triggered earthquakes occur in some places and not in others? there are 150,000 disposal wells in the united states that are permitted. of those, about 40,000 of the wells are associated with the disposal related to oil and gas activities. and yet we have only a dozen or so cases that -- of significantly large triggered earthquakes. most of the wells that do this injection are not triggering earthquakes.

another question is then once the earthquake occurs, what do you do? these three questions are the management questions, and they have a scientific basis which we're working on now to try to define so that we could get to this stage down here. what do you do to regulate or permit the activity, either before or after a significant earthquake occurs. what process change should be implemented? so i'm going to give you two end members of that sort of management challenge. and one is the fairly optimistic one which is held by some people who believe that the process can be controlled, and that we can minimize the risk to trigger an earthquake from a disposal activity. and that goes back to the very first line on my first slide, the experiment that was done in rangeley, colorado. this was an injection-triggered earthquake experiment. it was designed to determine whether or not an injection activity could induce an

earthquake and whether changes could the injection activity could ameliorate the earthquake hazard. so there's variations produced by controlled variations in the fluid pressure in a seismically active zone and the results of this experiment are said to have confirmed the predicted effect of fluid pressure on the earthquake activity, and indicate that the earthquakes may be controlled by manipulating the fluid pressure and the fault amount. so i was asked this question -- i think it was last year when the earthquakes were occurring in west virginia by one of the state managers responsible for permitting the activity. and not knowing what to do, he had already decided they were going to cut the volume in half, cut the permit volume in half. and the question, is that adequate? and, in fact n west virginia, earthquakes have continued in this same area. so the other end member of this

is that it's really an open question. and that's illustrated by this graph, which shows the maximum magnitude of a documented sequence of induced earthquakes, and for many places all around the world, this rma, rocky mountain arsenal, gey, is the geisers in california, ashtabulaa, ohio and so on. and these are distinguished by the cases of fluid injection and other causes. the largest earthquakes, those that occurred in gasle and uzbekistan are back up here, the one we don't know much about. but you see this trend, and that trend is maximum magnitude plotted against the log of the dimension affected by the fluid injection. essentially that, is the area affected by the continued pumping of water into a single injection well or a set of injection wells.

essentially, this phenomenon, that dimension in which the earthquakes are triggered by the injection activity, is a function of the volume of fluid that goes in. and so what you see here is actually a correlation between the volume of fluid and the maximum magnitude. this would indicate, contrary to the previous slide, that the more water, fluid you put down the hole, the more waste is disposed of, the larger the potential earthquake. and that dilemma, that research -- that's the research question which usgs is trying to address now, working with epa on some case studies. and we're also working on the theoretical side of the problem. which of these two end members is going to be defining of whether or not, once an earthquake occurs of a significant size, at a disposal site, one can alter the practice to minimize the risk. so finally, i want -- if you

need more information on this subject, i'm pointing you to our website. we have a frequently asked questions set for earthquakes that are induced by fluid injection and may answer some of the questions that you may have. thank you. >> thank you. a round of applause for all of our speakers. thank you. so we certainly encourage you to attend that if you wish. so if we can start with the questions and then our speakers

will do our best to address them. first question. >> how much money does a developer put into a pad, and then how much money does he make pulling gas out of it? >> i wanted -- [ inaudible ] >> no. i -- i don't think i can even answer that. >> another question? >> are you familiar with using propane as a fracking fluid, and is it as good as it sounds? >> would you repeat the question, please? >> the question was about use of propane as a fracking fluid. yeah, that's new to me.

and i have just heard about it in the media recently. so i -- about the only thing i can say, i know it would lessen the amount of water that's used on each one of the pads. what other chemicals it would involve, i don't know. >> i guess i have a kind of strange meta question. i'm struck by the contrast between the number of people who are here, presumably they have other things they can be doing. and the rather scientific and quiet tone of the presentation, very technical talk. i'm wondering -- i'm trying to understand why there's such great interest on the part of the audience, and yet the spirit of the presentation was rather technical and distant. i mean, there obviously is a great deal of concern on the part of people about this subject, and yet -- none of that

was really conveyed by the presentations that i heard. do any of you have any reservations about this whole process you would like to admit to us today? the whole process would like to admit to us today? >> again, i think at the beginning of the talk, i talked about how we don't take a position on these. we try to do the best science that we can to inform those who do make policy and inform the public, such as you, so you can be active in your community if you want to, about these things, and become informed. i was born and raised to be a scientist, and this is what i do. so it's not me taking an advocacy role for one position or another. >> we're very interested in the topic and the public and industry but we try to be dispassionate and address it in an objective matter as best as possible, so we convey the science but not the

interpretation of how the science can be applied. >> well, i would like to follow up on that. first of all, i enjoyed all of them, but the last one especially. but in terms of being totally objective, when i see that the only films that you're showing are from besides usgs are from industry, that is not what you might call fair and balanced, and i wish you would have shown a couple scenes from gasland which showed the true effects of these procedures. you didn't even mention the fact that there was a waver to the clean water act, sometimes known as the cheney waver, which said that these companies do not have to reveal what chemicals are going into the ground. yet you have -- yet you have government agencies approving this. my question is, well one question is do the companies have any responsibility in terms of damages caused by earthquakes, for example?

are they held accountable financially or in any other way, do you know? >> as far as i know, no. there's no direct -- i guess the better way to say this is i don't know of any loss which have been enacted which would put the companies at liability for triggering an earthquake that did any damage. >> thank you. with the exception of the last one, i thought you gave a pass to the industry in general. >> if i can real briefly address the comment about the films, ylg have to take credit for encouraging the use of the first film because i was putting together a presentation a up canal months ago and wanted to try to illustrate the concept of hydraulic fracturing, and i found that this film was very fair and straightforward, and

facical, and did a much, much better job than i could do. and then with respect to g gasland, all i know is that i was in it, if it helps you at all. >> i would like to also make one other comment about the regulatory aspects. the disposal of the produced waters from fracking operation actually is regulated by epa, epa has a program called underground protection control, and if you really want to dig into it, the well type, which is commonly associated with the disposal activity is the uic or underground injection control type two well. >> i might add, the presentation where you talk about stray gas, the gas that might iminate near the poor cement job, you're well away that the public is concerned about the occurrence of gas that could get up into

their water well or the public water supply, and the so-called stray gas has a number of sources, only one of which might be hide hide rufracturing is to understand the stray gas, are they coming from the shell gas units that dennis described in the portrayal but also coal bed and coal bed methane sources and also vegetative matter. understanding natural gas and the flux and rate at which they occur are part of the plan. >> i don't really have a question, but i want to congratulate you on recognizing the denver well experiments that jack haley and mg hubbard worked on back late '60s, and there

is -- they did publish the results in a science magazine article which seems to have been lost to an awful lot of investigators. but i think it's very relevant to what people should be looking at now. thank you. >> i think it's very much relevant, and that old paper has been certainly uncovered by quite a lot of people in the last year or so. >> they were some of our pioneers from the usgs and our earthquake program looking at what are the parameters to predict earthquakes. >> a lot of people don't seem to have found it yet. i'm glad you did. >> i'm just curious on the approximate distance from the bore hole that the fracs or the perfs extend, so the bore hole is horizontal, the fracs are

going up and down. ballpark, what is that distance? >> the data that i have seen, again, would be from industry papers and journals, indicate that in pennsylvania, there's some barriers to the propagation of the frac, so below the marcellus is the limestone, and it's a pretty significant barrier to propagation of the fractures below the marcellus. that is above it, which seems to be much less effective at limiting the propagation of the fracs. some of the data i have seen, hundreds to a thousand feet vertically i have seen. 5,000 feet the maximum. so you're tapping the marcellus

shale at depths of 5,000 and 8,000 feet in pennsylvania, so you've still got considerable amount of shale and sandstone between the freshwater, which is maybe 1,000 feet at maximum, and the frac interval of the well. in some other places, new york and ohio, some of these units may be tapped in shallower depths, which would maybe be more problematic. >> thanks. >> yes, i wanted to ask you a few questions. i'm glad to hear you're looking further into the sources of leakage of gases. and where they may be coming from. there's a recent study that i think is getting a lot of attention by, i believe it was, patron from noah in colorado that indicated that the emissions from a large field that included a lot of fracking

and other oil and gas operations was several times what the -- right. thank you. the emissions were several times as much as conventional inventories would indicate should come and a substantial amount of that, some of it was coming from the storage of natural gas liquids associated with these wells, but a substantial amount must have been coming from the well itself based upon the composition. and that's -- that raised a question of more specifically of what part of the operations are actually responsible for those leaks, which are very important to the greenhouse gas emission issue. i wunldfer you could comment on that? >> sure, i'll say that we are aware of that report that came out from noaa. and i'm not aware of anyone in the usgs working on that problem right now.

>> maybe i could ask one other question then. about up in pennsylvania, there was a recent interesting film shown on maryland public tv that talked a lot about pennsylvania. and it indicated that people were not -- had not been too unhappy over the years with natural gas from conventional wells in their backyards. but now our -- many of whom are at least very up happy about what is happening with fracking. and part of that is just an industrial activity that you pointed out on your presentations about having large pads and lots of trucks going by, et cetera. i wonder if you could put that in perspective because if there are many more wells necessary for natural